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USB Watchdog

Tags: Adapter Auto Restarter USB WatchDog do koparki BTC

Communication protocol

[238947.892900] usb 1-3.4: Product: USB2.0-Serial
[238947.899333] ch341 1-3.4:1.0: ch341-uart converter detected
[238947.906552] usb 1-3.4: ch341-uart converter now attached to ttyUSB0

Serial port parameters: 9600 8N1 

stty -F /dev/ttyUSB0 raw speed 9600

Each command is 1 byte value. It set watchdog threshold in deciseconds. Example commands: Commands sent to watchdog (1 byte):

  • 1 - next expected kick in 10 seconds. 
     echo -ne "\x01" > /dev/ttyUSB0
  • 36 - next expected kick in 360 seconds. 
     echo -ne "\x01" > /dev/ttyUSB0
  • 128 - status query. It responds with 0x81 
     echo -ne "\x80" > /dev/ttyUSB0
  • 255 - forced reset. 
     echo -ne "\xFF" > /dev/ttyUSB0

REMARK: Avoid low threshold. It is stored internally in watchdog, so after reset it is still low. In this case it is not possible to boot OS.

Default (after powerup) watchdog window is 170 sec (measured).

Daemon

https://github.com/niziak/usb-watchdog